homeland security correspondent bob orr is standing by in washington tonight. good evening, bob. >> reporter: good evening, jim. well, david petraeus is one of america's most decorated and reveered generals. as head of the c.i.a., he was in charge of the nation's most sensitive operations, but the ridgedly disciplined p/e was hiding his own dark secret. sources say c.i.a. director david petraeus was never the target of an f.b.i. investigation but when his name surfaced in another probe, agents became concerned that petraeus, or his e-mail accounts, may have been compromised. it all began a few months ago when a female acquaintance of the c.i.a. director received a series of harassing e-mails which apparently referenced petraeus. the woman, who sources say is not a government official, notified the f.b.i. federal agents quickly traced those e-mails back to petraeus' biographer, paula broadwell. a further investigation then revealed evidence of an extra marital affair, including numerous cryptic emales between the retired four-star general and broadwell. broadwel